This commit aims to change the behaviour of <a> links in readonly pad
widgets.
If the <a> redirects to a page that isn't in the domain (hostname
different of the current location hostname), we open it in a new
browser tab by adding a target.
Limitation: If you use the collaborative pad for a while and then
go back to a web editor html field, you'll have to edit each link
in order that the link opens a new tab by clicking on it.
Part of https://github.com/odoo/odoo/pull/64622
task-2377544
Thibault Libioulle
33efcabf93